jrups
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Abstract: In this work we propose the use of a hydro-dispersible polymer such as the poly vinyl acetate as a binder for the production of electrodes for lithium-ion batteries. To increase the film forming properties of the polymer the poly vinyl was added with triacetin that acts as a plasticizer. The electrochemical stability of the polymer was tested by a polarizing electrode, formed by mixing the polymer with carbon. Subsequently, an electrode tape was prepared by using LiNi0.5Mn1.5O4 as the active material and characterized by SEM, EDS and TGA. Lithium metal cells were assembled and tested to evaluate specific capacity, power and energy density at various discharge rates. The cycle life of the cell was evaluated by galvanostatic charge/discharge cycles. The tests showed that the electrodes prepared with PVA plasticized with triacetin have very good electrochemical performance in terms of capacity retention as a function of the discharge rate and the cycle number. Our work demonstrates that the use of triacetin to plasticize the PVA allows to increase the electrochemical stability of the electrode likely due to an improvement of the slurry filmability. The proposed method could represent a promising technology for the production of long-term performance lithium batteries.. Keywords: Poly vinyl acetate, triacetin, composite cathode, lithium battery, LiNi0.5Mn1.5O4 |
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Abstract: In this work we propose the use of a hydro-dispersible polymer such as the poly vinyl acetate as a binder for the production of electrodes for lithium-ion batteries. To increase the film forming properties of the polymer the poly vinyl was added with triacetin that acts as a plasticizer. The electrochemical stability of the polymer was tested by a polarizing electrode, formed by mixing the polymer with carbon. Subsequently, an electrode tape was prepared by using LiNi0.5Mn1.5O4 as the active material and characterized by SEM, EDS and TGA. Lithium metal cells were assembled and tested to evaluate specific capacity, power and energy density at various discharge rates. The cycle life of the cell was evaluated by galvanostatic charge/discharge cycles. The tests showed that the electrodes prepared with PVA plasticized with triacetin have very good electrochemical performance in terms of capacity retention as a function of the discharge rate and the cycle number. Our work demonstrates that the use of triacetin to plasticize the PVA allows to increase the electrochemical stability of the electrode likely due to an improvement of the slurry filmability. The proposed method could represent a promising technology for the production of long-term performance lithium batteries.. Keywords: Radical polymerization, Polystyrene-b-Poly(4-vinylpyridine), Inverse Gas Chromatography, Specific interactions, Acid and Base Constants. |
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Abstract: The composite hydrogels based on rice straw (RS) and N-vinyl-2-pyrrolidone (NVP) or acrylamide (AAm) were successfully prepared by gamma irradiation. The effect of the radiation dose and the monomer content on the gel percent was studied. The composite hydrogels were confirmed by (FTIR), (TGA) and (SEM). It was found that the diffusion of water into the prepared composites was Fickian character. The removal of congo red (CR) and methyl orange (MO) dyes by (NVP/RS) and (AAm/RS) composite hydrogels were investigated as a function of the pH, contact time, initial dye concentration solution and temperature. It was achieved that the adsorption capacity of (NVP/RS) composite hydrogel towards (CR) and (MO) was higher than (AAm/RS) one. The kinetic data was tested by the pseudo-first-order and the pseudo-second-order kinetic models. The adsorption isotherm was closely fitted with the Freundlich model for adsorption of CR and MO onto (NVP/RS) and the Langmuir model for adsorption of the dyes onto (AAm/RS). A high adsorption capacity was obtained in the second adsorption cycle of MO onto the composite hydrogels loaded with CR. Improvement in the adsorption of MO onto (NVP/RS) and (AAm/ RS) composite hydrogels loaded with Co(II). Keyword: Agricultural waste, Kinetics, isotherm, Radiation, secondary adsorption.
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Abstract: In this study, novel star-shaped polymers of β-cyclodextrin (β-CD)–poly (glycidyl methacrylate) (PGMA) were prepared by atom transfer radical polymerization (ATRP), formed from GMA and β-CD. In addition, the structure, properties and hydrophilicity of the β-CD-PGMA polymers thus prepared were systematically analyzed. 1,10-phenanthroline monohydrate (Phen)/β-CD-PGMA drug-loaded microspheres were prepared by emulsion solvent evaporation. The optimum preparation conditions were determined by orthogonal tests. Analysis results indicated that the performance of star-shaped polymers of β-CD-PGMA clearly changes, resulting in the increase of the contact angle from 17° to 72.5°, and their thermal degradation temperature was enhanced from 260 °C to 401 °C. Moreover, β-CD-PGMA drug-loaded microspheres with a smooth, spherical surface were successfully prepared, and the drug-loading capacity and average particle size of drug-loaded microspheres were 26.67 % and 10 μm, respectively. Drug release tests indicated that the release behavior of β-CD-PGMA drug-loaded microspheres conformed to Higuchi release kinetics, which exhibited a significant drug delivery capability. The release rate and utilization of β-CD-PGMA were greater than that of β-CD, demonstrating that β-CD-PGMA was more suitable as a drug delivery material. Keywords: β-cyclodextrin, glycidyl methacrylate, atom transfer radical polymerization, drug-loaded microspheres, star-shaped polymers, release kinetics. |
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Abstract: This work proposes a technique for isolation of bacteria using magnetic nanoparticles. The magnetic nanoparticles that are prepared by a sol-gel method using citric acid and nano-ferrites are characterized for structural and morphology by X-ray diffraction (XRD) and Transmission electron microscope (TEM), respectively. The prepared nano-ferrites coated with poly vinyl alcohol (PVA) over platinum electrode are used for detection of Bacillus Cereus. The isolated bacterial cells from colloidal solution are treated with zinc ferrite for 12 h, and it is observed that the cells are coagulated with the nanoparticle when allowed to settle down. This is further filtered by different size of filter paper to get less than 0.1% of cells in water. Various electrochemical parameters like cyclovoltammetry (CV), sweep step function, Tafel plot, AC impedance are studied employing the modified platinum electrode. It is observed through CV graph that the peaks are formed at -0.25 V due to the oxidation of bacterial cells, which is further supported by sweep step function graph. Therefore, this is one of the economically efficient techniques to detect and isolate the Bacillus cereus from a colloidal solution. Keywords: Bacillus cereus, Magnetic nanoparticle, Cyclovoltammetry, Sweep step function. |